The field of the invention relates generally to electric motors, and more specifically, to methods and systems for controlling electric motors.
Electric motor drive controllers typically include an inverter for driving an electric motor. The inverter converts a direct current (DC) bus voltage to an alternating current (AC) voltage by switching upper and lower switching devices that are coupled in series using pulse width modulation (PWM). If the upper and lower switching devices are turned on at the same time, short-circuiting between the upper and lower switching devices may occur, resulting in damage to the switching devices. To prevent such short-circuiting, a deadtime is provided where both the upper and lower switching devices are off. The presence of deadtime, however, may cause distortion of current supplied to the electric motor and pulsation of torque. Moreover, deadtime introduces error in voltage estimation in low voltage and low speed regions of electric motor operation. These issues are commonly referred to by the term “deadtime effect”.